Method for using a pump set having secure loading features

ABSTRACT

A method of using a pump set on a pump to deliver a supply of liquid to a patient. The pumping apparatus has a control system for controlling operation of the pump. An electromagnetic radiation source is controlled by the control system to emit an electromagnetic radiation signal in a direction for striking a safety interlock device associated with the pump set. The safety interlock device affects the direction of the electromagnetic radiation. An electromagnetic radiation detector is operatively connected to the control system for receiving the electromagnetic radiation signal when the direction is affected by the safety interlock device, and provides an indication to the control system that the pump set conduit is properly positioned in the pump. The pump is controlled to pump liquid in the pump set only when electromagnetic radiation emitted from the first source is detected by the first detector.

BACKGROUND

This invention relates generally to pump sets and pumps to deliverfluids to patients by way of a flow control apparatus, and moreparticularly to a method for using a pump set having a safety interlockdevice to control operation of a pump.

Administering fluids containing medicine or nutrition to a patient iswell known in the art. Fluids can be delivered to patients by gravityflow, but often are delivered to the patient by a pump set loaded on aflow control apparatus, such as a peristaltic pump, which delivers fluidto the patient at a controlled rate of delivery. A peristaltic pumpusually comprises a housing that includes a rotor or the likeoperatively engaged to at least one motor through a gearbox. The rotordrives fluid through the tubing of the pump set by the peristalticaction effected by rotation of the rotor by the motor. The motor isoperatively connected to a rotatable shaft that drives the rotor, whichin turn progressively compresses the tubing and drives the fluid at acontrolled rate through the pump set. A controller operates the motor todrive the rotor. Other types of peristaltic pumps not employing rotorsare also known.

In order for the pump to deliver an accurate amount of fluidcorresponding with the flow parameters programmed into the pump, theadministration feeding set must be correctly loaded on the pump. If thepump set is misaligned in the pump, the pump may deliver an inaccurateamount of fluid to a patient or the pump generates a low flow alarmrequiring the condition to be examined and the set reloaded. Existingpumps have systems to detect whether the pump set is properly loaded. Anexample of such a pump having a detection system is shown in co-assignedU.S. Pat. No. 4,913,703, entitled SAFETY INTERLOCK SYSTEM FOR MEDICALFLUID PUMPS, the disclosure of which is incorporated by reference. Thissystem uses a magnet on the pump set which is detected by circuitry inthe pump. It would be desirable to provide a pump set that can bedetected but which does not require each pump set to have a magnet.

SUMMARY OF INVENTION

In one aspect of the present invention, a method of using a feeding seton an enteral feeding pump generally comprises inserting an interlockdevice of the feeding set into a recess of the enteral feeding pump.Infrared radiation is intermittently emitted in a direction for strikingthe inserted interlock device and is transmitted and internallyreflected within the interlock device to redirect the infrared radiationtoward a first detector when the interlock device is properly insertedin the pump recess. The first detector detects the infrared radiationredirected within the interlock device. A visible light emitter isintermittently energized only after infrared radiation has been detectedby the first detector. Visible light is filtered with the interlockdevice to prevent transmission through the interlock device, and asecond detector is read to verify that visible light emitted by thevisible light emitter has been blocked. Operation of the enteral feedingpump is enabled to pump nutrient liquid in the feeding set in responseto detection of infrared radiation by the first detector and theverification that no visible light is detected by the second detector.

In another aspect of the present invention, a method of using a feedingset on an enteral feeding pump. The feeding set has an interlock deviceadapted to be inserted into a recess of the enteral feeding pump. Themethod generally comprises inserting the interlock device into therecess of the enteral feeding pump. Electromagnetic radiation is emittedin a direction for striking the inserted interlock device and at least aportion of the electromagnetic radiation striking the interlock deviceis detected when the interlock device is properly inserted in the pumprecess. Operation of the enteral feeding pump to pump nutrient liquid inthe feeding set is enabled in response to the detected electromagneticradiation.

In yet another aspect of the present invention, a method for controllinga pumping apparatus capable of mounting a pump set having a safetyinterlock device thereon generally comprises emitting electromagneticradiation from a first source of electromagnetic radiation in adirection for striking the safety interlock device of the pump set. Afirst electromagnetic radiation detector is activated to detectelectromagnetic radiation striking the first detector. Electromagneticradiation is emitted from a second source of electromagnetic radiationin a direction for striking the safety interlock device of the pump set.A second electromagnetic radiation detector is activated to detectelectromagnetic radiation striking the second detector. The pumpingapparatus is controlled to operate for pumping fluid in the pump setonly when electromagnetic radiation emitted from the first source isdetected by the first detector and when the second detector does notdetect electromagnetic radiation.

Various refinements exist of the features noted in relation to theabove-mentioned aspects of the present invention. Further features mayalso be incorporated in the above-mentioned aspects of the presentinvention as well. These refinements and additional features may existindividually or in any combination. For instance, various featuresdiscussed below in relation to any of the illustrated embodiments of thepresent invention may be incorporated into any of the above-describedaspects of the present invention, alone or in any combination.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective of an enteral feeding pump showing a fragmentaryportion of a feeding set received on the pump;

FIG. 2 is a perspective of the pump;

FIG. 3 is an elevation of the administration feeding set;

FIG. 4 is a block diagram showing the elements of the pump

FIG. 5 is an enlarged, fragmentary section of the pump and a safetyinterlock device of a first embodiment;

FIG. 6 is a top plan view of FIG. 5;

FIG. 6A is a schematic diagram similar to FIG. 6 showing propagation ofa light ray in the safety interlock device;

FIG. 7 is an enlarged, fragmentary section of a pump and safetyinterlock device of a second embodiment;

FIG. 7A is an enlarged, fragmentary section of a pump and a safetyinterlock device of a third embodiment;

FIG. 8 is an enlarged, fragmentary section of a pump and a safetyinterlock device of a fourth embodiment;

FIG. 9 is an enlarged, fragmentary section of a pump and a safetyinterlock device of a fifth embodiment;

FIG. 10 is an enlarged, fragmentary section of a pump and a safetyinterlock device of a sixth embodiment;

FIG. 11 is a state diagram of a microprocessor of the pump;

FIG. 12 is a an enlarged, fragmentary section of a pump and a safetyinterlock device of a seventh embodiment;

FIG. 13 is an enlarged, fragmentary section of a pump and a safetyinterlock device of an eighth embodiment;

FIG. 14 is a top plan view of a pump and a safety interlock device of aninth embodiment;

FIG. 15 is a state diagram of a microprocessor of the pump of the ninthembodiment;

FIG. 16 is a block diagram showing a feeding set and elements of thepump of the ninth embodiment;

FIG. 17 is a flow chart showing operation of a software subsystem usedwith the pump of the ninth embodiment that pulses an infrared emitter;

FIG. 18 is a flow chart showing operation of another software subsystemthat can be used with the pump of the ninth embodiment that does notpulse the infrared emitter;

FIG. 19 is a state diagram showing conditions encountered in executingthe instructions of the software subsystem shown in FIG. 18;

FIG. 20 is a fragmentary top plan view of a pump and safety interlockdevice of a tenth embodiment;

FIG. 21 is an enlarged fragmentary section taken along line 21-21 ofFIG. 20; and

FIG. 22 is an enlarged, fragmentary section similar to FIG. 21 butshowing a safety interlock device of an eleventh embodiment.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

DETAILED DESCRIPTION

Referring now to the drawings, an enteral feeding pump (broadly, “apumping apparatus”) constructed according to the principles of thepresent invention is generally indicated at 1. The feeding pumpcomprises a housing generally indicated at 3 that is constructed so asto mount an administration feeding set (broadly, a “pump set”) generallyindicated at 5 (see FIGS. 1 and 3). It will be appreciated that“housing” as used herein may include many forms of supporting structures(not shown), including without limitation multi-part structures andstructures that do not enclose or house the working components of thepump 1. The pump 1 also has a display screen 9 on the front of thehousing 3 that is capable of displaying information about the statusand/or operation of the pump. Buttons 11 on the side of the displayscreen 9 are provided for use in controlling and obtaining informationfrom the pump 1. It will be understood that although the illustratedpump 1 is an enteral feeding pump, the present invention has applicationto other types of peristaltic pumps (not shown), including medicalinfusion pumps. A pump of the same general type as described herein isshown in co-assigned U.S. Pat. No. 4,909,797 entitled ENTERAL DELIVERYSET WITH SHADED DRIP CHAMBER, the disclosure of which is incorporatedherein by reference.

The enteral feeding pump 1 further includes a pumping unit (indicatedgenerally at 23) comprising a pump motor 25 located in the housing 3 andshown schematically in FIG. 4. An electrical cord 27 extends from thehousing 3 for connection to a source of electrical power for the motor25. Alternatively, or in addition, a battery (not shown) may be receivedin the housing 3 for powering the pump motor 25. The pumping unit 23further includes a rotor (generally indicated at 37) mounted on a rotorshaft (not shown) of the pumping unit. The rotor 37 includes an innerdisk 39, an outer disk 41 and three rollers 43 (only one is shown)mounted between the inner and outer disks for rotation about theirlongitudinal axes relative to the disks. In the illustrated embodiment,the pump motor 25, rotor shaft and rotor 37 may broadly be considered “apumping device”. The pump housing 3 includes a first lower recess 45above the rotor 37 and a second lower recess 47 generally adjacent thefirst lower recess. The housing 3 has an upper recess 49 generallyaxially aligned with the first lower recess 45 and a shoulder 51 at thebottom of the upper recess for receiving and holding part of the feedingset 5. A curved recess 53 in the housing 3 above the second lower recess47 receives and holds another part of the administration feeding set 5in place. The lower recesses 45, 47, upper recess 49 and curved recess51 may broadly be considered, individually or as a group, “a receivingportion” of the housing 3 that receives parts of the administrationfeeding set 5 in a manner that will be described in more detailhereinafter.

Referring now to FIG. 3, the administration feeding set 5 comprisestubing (broadly, “a conduit”) indicated generally at 55 that provides afluid pathway between at least one source of fluid and a patient. Tubing55 can be made of a medical grade, deformable silicone and comprisesfirst tube section 57 connected between a drip chamber 59 and a safetyinterlock device, generally indicated at 61. A second tube section 63 isconnected to the safety interlock device 61 and at an outlet of thetubing 55 to a connector, such as a barbed connector 65, suitable forconnection to a gastrostomy device (not shown) attached to a patient.Third tube section 67 is connected at an inlet of the tubing 55 to a bag69 of nutrient liquid and to the drip chamber 59. As previously stated,pump sets of different constructions may be used, for example arecertification set (not shown) may be used to verify and/or correct thepump accuracy. The pump 1 can be configured to automatically recognizewhat kind of set is installed and to alter its operation to conform tothat called for by the particular pump set. Still further, the pump 1can be configured to detect with sensors whether the first tube section57 is properly installed on the pump.

As shown in FIG. 3, the safety interlock device 61 connects first tubesection 57 and the second tube section 63 of the administration feedingset 5. The safety interlock device 61 has a central axial bore 81 toallow the flow of fluid between the first tube section 57 and the secondtube section 63 (see, FIG. 5). The safety interlock device 61 has anupper cylindrical portion 83 that receives a portion of the tube 57, anelectromagnetic radiation propagation affecting member 87 that extendsradially outward from the upper cylindrical portion, and a lowercylindrical portion 89 that is received in the second tube section 63for attaching the second tube section to the safety interlock device. Itis to be understood that the safety interlock device 61, and inparticular the member 87 may be separate from the administration feedingset 5, and/or may be attached to the administration feeding set in sucha way that liquid does not pass through the safety interlock device. Theelectromagnetic radiation propagation affecting member 87 is sized to bereceived on a seat, indicated generally at 91, formed at the bottom ofthe second lower recess 47 in the pump 1 when the administration feedingset 5 is properly loaded on the pump. In the illustrated embodiment, theseat 91 is generally semi-cylindrical to correspond with the shape ofthe safety interlock device 61 and includes an axially facing surface 95in the second lower recess 47 and a radially facing surface 99 in thesecond lower recess 47. In this first and most other embodiments, properfunctioning of the pump 1 is generally achieved when the radiationpropagation affecting member 87 is seated in substantially face-to-facerelation with the axially facing surface 95 of the seat 91. However, therotation orientation of the member 87, within the seat 91, about itsaxis is generally not pertinent to operation. In a few embodiments(noted hereinafter) a particular orientation of the member 87 is useful,in which cases keying structures are provided. Other ways of positioningthe propagation affecting member 87 may be used within the scope of thepresent invention. The safety interlock device 61 and the seat 91 in thehousing 3 may be shaped to prevent the administration feeding set 5 frombeing accidentally dislodged and to prevent the use of non-compliantfeeding sets that do not have the safety interlock device. In theillustrated embodiment, the safety interlock device 61 and seat 91 aregenerally cylindrical in shape but it is understood that other shapes(e.g., hex-shaped) may be used for the safety interlock device and theseat. As will be discussed in more detail below, the safety interlockdevice 61 is comprised of a material (e.g., a thermoplastic polymerresin such as polysulfone thermoplastic resin or other suitablematerials) that is opaque to visible light but easily transmitselectromagnetic radiation in the infrared range.

Generally speaking, a safety interlock device is able to affect thepropagation of electromagnetic radiation by diffusion, diffraction,reflection and/or refraction, or any combination of diffusion,diffraction, reflection and/or refraction. Diffusion is generallyunderstood as the scattering of electromagnetic radiation rays eitherwhen reflected from a rough surface or during transmission ofelectromagnetic radiation through a translucent medium. Diffraction isgenerally understood as the bending of electromagnetic radiation raysaround the edges of opaque objects. Reflection is understood as thereturn or change in the direction of travel of particles or radiantenergy which impinges on a surface but does not enter the substanceproviding the reflecting surface. Refraction is understood as the changein direction of motion of a ray of radiant energy as it passes obliquelyfrom one medium into another in which the speeds of propagation aredifferent (e.g., media of different densities). The amount of refractionis based on the index of refraction dependent in part on the density ofthe material facing the medium.

The pump 1 can be programmed or otherwise controlled for operation in adesired manner. For instance, the pump 1 can begin operation to providefeeding fluids from bag 69 to the patient. The care giver may select,for example, the amount of fluid to be delivered, the rate at which thefluid is to be delivered and the frequency of fluid delivery. As shownin FIG. 4, the pump 1 has a controller 77 (broadly, “a control system”)including a microprocessor 79 that allows it to accept programmingand/or to include pre-programmed operational routines that can beinitiated by the care giver. The microprocessor 79 controls pumpelectronics 80 that operate the motor 25. A software subsystem 82 isused to determine if the feeding set 5 has been positioned properly onthe pump 1.

In the first embodiment, the pump includes an infrared (“IR”) emitter105 (broadly, “a source of electromagnetic radiation”) housed in thesecond lower recess 47. Referring to FIGS. 5 and 6, the IR emitter 105is operatively connected to the controller 77 for emitting anelectromagnetic signal having a (“first”) wavelength in the infraredrange in a direction for striking the safety interlock device 61 of thefeeding set 5. In the illustrated embodiment, the source ofelectromagnetic radiation is an infrared (IR) emitter 105 but it isunderstood that other types of sources of electromagnetic radiation maybe used without departing from the scope of this invention. An infrared(“IR”) detector 109 located in the second lower recess 47 is operativelyconnected to the controller 77 for receiving the infrared signal fromthe IR emitter 105 and providing an indication to the controller thatthe feeding set 5 is properly positioned in the pump 1. In theillustrated embodiment, the IR detector 109 (broadly, “a first sensor”)detects infrared radiation but it is understood that electromagneticradiation sensors that detect other types of electromagnetic radiationmay be used without departing from the scope of this invention. The IRdetector 109 distinguishes infrared radiation from other types ofelectromagnetic radiation (e.g., visible or ultraviolet light). Avisible light detector 111 (broadly, “a second electromagnetic radiationdetector” and “a second sensor”) is housed in the second lower recess 47generally adjacent the IR detector 109. The visible light detector 111provides a signal to the controller 77 when visible light from thesurrounding environment (e.g., electromagnetic radiation of a secondwavelength) is detected to indicate that the safety interlock device 61is not mounted in the second lower recess 47 in a position that blocksvisible light from reaching the detector. Preferably, the visible lightdetector 111 is configured to detect electromagnetic radiation in thevisible range, but not to detect electromagnetic radiation outside thevisible range (e.g., infrared radiation). A second electromagneticradiation detector could be configured to detect electromagneticradiation in other ranges, such as in the ultraviolet range. Thus, thevisible light detector 111 can distinguish visible light from infraredradiation. As used herein, electromagnetic radiation of a “first” or“second” wavelength is intended in each case to encompass a range ofwavelengths, such as wavelengths falling in the infrared range, visiblerange and/or ultraviolet range.

Other sensors (not shown), such as a sensor that determines the type ofpump set that has been placed in the pump 1 and a flow monitoring sensorcan be in communication with the controller 77 to facilitate accurateoperation of the pump. The IR emitter 105 is positioned in an alcove 113in the second lower recess 47 of the housing 3 so that electromagneticradiation (indicated by arrows A1 in FIG. 6) from the emitter isdirected to the electromagnetic radiation propagation affecting member87 of the safety interlock device 61 (see also, FIG. 5). When the safetyinterlock device 61 is properly located on the seat 91, the infraredradiation from the IR emitter 105 is diffused through theelectromagnetic radiation propagation affecting member 87 and internallyreflected so that the infrared radiation is directed to and detected bythe IR detector 109. Diffusion may be enhanced by the addition ofparticulates to the material of the member 87. In this first embodiment(and other embodiments) the infrared radiation propagation is affectedprimarily through internal reflection. Other effects on infraredradiation propagation, such as diffusion, may also assist. However, anyinfrared radiation that is refracted is minimal and does not contributeto the infrared radiation signal seen by the IR detector 109 (i.e.,refraction causes a reduction in signal strength). The IR detector ispositioned in an alcove 117 in the radially facing surface 99 of theseat 91 and the visible light detector 111 is positioned in an alcove119. The alcoves 113, 117, 119 recess the IR emitter 105 and the IR andvisible light detectors 109, 111 to protect them from physical contactwith the propagation affecting member 87. Although not shown, a clearplastic window may enclose each of the emitter 105 and the detectors109, 111 within their corresponding alcoves 113, 117, 119 for additionalprotection. Moreover, the alcoves 117 and 119 help to shield thedetectors 109 and 111 from ambient electromagnetic radiation (which mayinclude both visible light and infrared radiation).

In the illustrated first embodiment, the IR emitter 105 is locatedapproximately 90 degrees from the IR detector 109. When the feeding set5 is not loaded in the second lower recess 47 and the electromagneticradiation propagation affecting member 87 is not received on the seat91, the infrared radiation from the IR emitter 105 is not detected bythe IR detector 109. Also when the safety interlock device 61 is notreceived on the seat 91, visible light from outside of the pump 1 (i.e.,ambient light) may enter the second lower recess 47 and is detected bythe visible light detector 111. The propagation affecting member 87 ispreferably constructed of a material that transmits infrared radiation,but is opaque to visible light. The propagation affecting member 87 maybe monolithic or may have other constructions such as an outer layer(not shown) that transmits infrared radiation, but does not transmitvisible light and an inner layer or core that is transmissive to bothinfrared radiation and visible electromagnetic radiation.

Referring now to FIG. 6A, movement of infrared radiation within theelectromagnetic radiation propagation affecting member 87 isschematically illustrated. The IR emitter 105 emits infrared radiationin a cone toward the side of the member 87. The IR emitter 105 isarranged generally perpendicular to the immediately adjacent side of themember 87. The centerline CL of the cone is denoted in the drawing. Forsimplicity, we will ignore diffusion and look at a ray R1 of radiationthat is a bisector of approximately one half of the cone. The ray R1 isrepresentative of the nominal path of infrared radiation in this half ofthe cone. The other half of the cone (i.e., that portion above thecenterline CL in FIG. 6A) is believed to be of small or no use inproviding a light signal capable of being detected by the IR detector109. The ray R1 strikes the side of the propagation affecting member 87at an angle so that it enters the member rather than being reflectedback. The ray R1 travels generally toward the center of the member 87until it reaches a boundary B (broadly, “an inner boundary region”)around the axial bore 81 of the member. The ray R1 is reflected backtoward the side of the member 87 where a good percentage of the ray isreflected back toward the center. At the boundary B, the ray R1 is oncemore reflected back toward the side of the member 87. Finally, the raystrikes the interior side of the member 87 at a location that is about96 degrees away from the location of the IR emitter 105. It has beenfound that a particularly high level of intensity of infrared radiationescapes the member 87 at this location. Accordingly, the IR detector 109is preferably positioned here, or in a range of around 75-105 degrees.Another higher intensity node is found at a location around 49 degreesfrom the IR emitter 105, as would be expected from the reflection.

The boundary B of the electromagnetic radiation propagation affectingmember 87 can be made of the same material as the remainder of themember. The material at the boundary B may be more “polished” (i.e.,more specular) than elsewhere to increase its ability to reflectelectromagnetic radiation impinging upon the boundary. However, it isalso possible that the central part of the member 87 could be formed ofa separate material. In that case, the member 87 would be formed of aninner and an outer member, such as described below in regard to FIG. 22.In use, the administration feeding set feeding fluid bag 69 can be hungfrom a suitable support, such as an IV pole (not shown). The dripchamber 59 can be placed in the first lower recess 45 and upper recess49 in an operating position as shown in FIG. 1. The first tube section57 is placed around the lower part of the rotor 37 and the safetyinterlock device 61 is placed on the seat 91 at the bottom of the secondlower recess 47. The seat 91 in the second lower recess 47 is generallylocated so that the safety interlock device 61 can be placed into thesecond lower recess at a location in which the first tube section 57 issubstantially stretched around the rotor 37. The IR emitter 105 and IRdetector 109 may intermittently or continuously check for the presenceof the properly loaded feeding set 5. When the safety interlock device61 is received in a proper operating position on the seat 91, theinfrared signal from the IR emitter 105 is directed to theelectromagnetic radiation propagation affecting member 87. Theelectromagnetic radiation propagation affecting member admits theinfrared radiation into its interior where the electromagnetic radiationis diffused and internally reflected (see FIGS. 6 and 6A). Some of theinfrared radiation which is redirected outward and impinges the outerboundary of the electromagnetic radiation propagation affecting member87 substantially at right angles thereto passes out of theelectromagnetic radiation propagation affecting member. Some of theescaping infrared radiation is directed toward the IR detector 109. TheIR detector is periodically operated and detects the presence ofinfrared radiation when the feeding set 5 has been properly loaded onthe pump. It is understood that the IR detector 109 is preferably unableto detect electromagnetic radiation having a wavelength in the visiblelight region of the electromagnetic spectrum. Upon detection of theinfrared signal, the IR detector 109 sends a corresponding signal to themicroprocessor 79. Also, when the safety interlock device 61 is loadedonto the seat 91, visible light is blocked by the member 87 fromreaching the visible light detector 111. When the set 5 is loaded, thevisible light detector 111 sends a signal to the microprocessor 79 toindicate that visible light is blocked and the pump 1 may be operated.

In one embodiment, the IR emitter 105 and IR detector 109 are bothoperated intermittently to detect the presence of the safety interlockdevice 61 on the seat 91. The IR emitter 10 s is operated to generate apattern of infrared radiation pulses. The IR detector 109 is operated ina series of detector activations or pulses that check for the presenceof electromagnetic radiation from the IR emitter 105. Typically, thenumber of activations from the IR detector 109 will be greater than thenumber of pulses from the IR emitter 105 for a given period of time. Forexample, the IR detector 109 may have two activations in a three secondtime period and the IR emitter 105 may be programmed to generate onepulse of infrared radiation during the three second time period. Duringthe three second time period, the pump 1 has a ratio of detectoractivations to emitter activations of about 2:1. It is understood thatthe pump 1 may have other ratios and that the IR emitter 105 and IRdetector 109 may operate in other predetermined intermittent patternswithout departing from the scope of this invention. The IR detector 109and the controller 77 may be configured for recognizing a particular,and for example irregular, pattern of activations of the IR emitter 105.

FIG. 7 shows a seat 191 and a safety interlock device 121 of a secondembodiment of the present invention. The safety interlock device 121 ofthis embodiment has a electromagnetic radiation propagation affectingmember 123 with an angled annular surface 125. The IR emitter 129 islocated in an alcove 131 in a radially facing surface 132 of a seat 191of housing 143 and is positioned to direct infrared radiation toward thesafety interlock device 121 in a similar manner as the first embodiment.In the embodiment of FIG. 7, the IR detector 133 and visible lightdetector 135 are located in respective alcoves 137, 139 in an axiallyfacing surface 141 of the seat 191. The angled annular surface 125 isreflective so that it reflects infrared radiation from the IR emitter129 downward to the IR detector 133 when the safety interlock device 121is received on the seat 191 of the housing 143. When the safetyinterlock device 121 is not properly received in the seat 191, visibleambient light can be detected by the visible light detector 135.

FIG. 7A shows a seat 159 and a safety interlock device 161 of a thirdembodiment of the present invention. In this embodiment, the safetyinterlock device 161 includes a reflector 165 on the external radialsurface of an electromagnetic radiation propagation affecting member167. The reflector 165 may be a layer of reflective tape or a layer ofpolished metal affixed to the remainder of the electromagnetic radiationpropagation affecting member 167. In the embodiment of FIG. 7A, the IRemitter 169, the IR detector 171, and the visible light detector 173 arearranged in an alcove 175 in a radially facing surface 177 of housing179 in a manner such that the three devices are generally verticallyaligned and parallel to each other. It is understood the IR emitter 169,IR detector 171, and visible light detector 173 may be otherwisearranged. When the safety interlock device 161 is received in the seat159, the infrared radiation emitted from the IR emitter 169 is reflectedoff the reflector 165 and transmitted to the IR detector 171 and ambientvisible light is blocked from detection by the visible light detector173. When the safety interlock device 161 is not loaded in the seat 159,infrared radiation is not transmitted to the IR detector 171 and ambientvisible light can be detected by the visible light detector 173.

FIG. 8 shows a seat 189 and safety interlock device 191 of a fourthembodiment of the present invention. As in the prior embodiments, thesafety interlock device 191 can be removably positioned on the seat 191and thereby releasably attached to the pump by the user or caregiver. Inthis embodiment, the safety interlock device 191 includes a light pipe195 (“an electromagnetic radiation propagation affecting member”)received in the seat 189 of the housing 199 when the feeding set 201 isloaded on the pump. The light pipe 195 includes an outer annular portion205, an angled annular wall 207, and a central portion 209 between theangled wall and the upper portion 211 that receives a tube 213 of thefeeding set 201. As shown in FIG. 8, the IR emitter 217 and IR detector219 are both housed below a bottom wall 221 of the seat 189. The IRemitter 217 directs infrared radiation upward to the outer annularportion 205 of the light pipe 195 that is reflected by the angledannular wall 207 through the central portion 209 of the light pipe(around a central fluid passage 218) before being reflected to the IRdetector 219 by the angled annular wall 207 on the opposite side of thelight pipe. When the safety interlock device 191 is not properly seatedon the seat 189 in the loaded position of the feeding set 201, the IRsignal from the IR emitter 217 is not transmitted through the light pipe195 to the IR detector 219. A visible light detector (not shown) may bepresent for use in detecting ambient light as in earlier embodiments ofthe invention.

FIG. 9 shows a seat 231 and a safety interlock device 235 of a fifthembodiment of the present invention. This safety interlock device 235 ofthis embodiment comprises an infrared radiation transmissive materialthat also refracts the infrared radiation transmitted through the safetyinterlock device. The safety interlock device 235 has a generallypolygonal shape. Opposite sides 236 of the safety interlock device 235are angled parallel to each other. The seat 231 is keyed to receive thesafety interlock device in the particular orientation illustrated inFIG. 9 so that electromagnetic radiation is refracted in the desiredmanner, as will be described. An IR emitter 237, an upper IR detector239 (broadly, “a second detector”), and a lower IR detector 241(broadly, “a first detector”) are positioned for sensing if anadministration feeding set 245 has been properly loaded into the pump.The upper and lower IR detectors 239, 241 are positioned on the oppositeside of the seat 231 from the IR emitter 237 such that the emitter andthe detectors are oriented at approximately 180 degrees with respect toeach other. Also, the upper IR detector 239 and lower IR detector 241are spaced apart a distance D so that when infrared radiation is passedthrough the safety interlock device 235, the radiation (as indicated atarrow A5) is refracted or bent downward so that the lower IR detector241 senses the presence of infrared radiation and sends a signal to themicroprocessor to enable operation of the pump. The sides of the safetyinterlock device 25 are angled parallel to each other so that refractionof the infrared radiation is directed by the refraction to the lower IRdetector 241. When the safety interlock device 235 is not loaded in theseat 231 of the pump, the infrared radiation from the IR emitter 237 (asindicated by phantom arrow A6) passes through the seat such that thebeam of infrared radiation is directed to only the upper IR detector239, which sends a signal to the controller to disable operation of thepump. The density and width of the safety interlock device 235 affectsthe distance D between the upper detector 239 and the lower detector 241so that if an feeding set is used having a safety interlock device madeof a material having a different density and/or width, theelectromagnetic radiation will not be refracted the proper distance toimpinge on the lower IR detector 241 even if the feeding set is properlyloaded. A visible light detector (not shown) may be present for use indetecting ambient light as in earlier embodiments of the invention.

FIG. 10 shows a seat 271 and safety interlock device 273 of a sixthembodiment of the present invention. The safety interlock device 273 ofthis embodiment is generally similar to the first embodiment butincludes a layer 275 of infrared radiation blocking material on theexternal surface of the safety interlock device. As in the firstembodiment, the safety interlock device 273 includes an electromagneticradiation propagation affecting member 279 that transmits infraredradiation through the safety interlock device. The external radialsurface 281 of the electromagnetic radiation propagation affectingmember 279 is free from infrared radiation blocking material as thissurface is used to receive the infrared signal from the IR emitter 285so that the IR signal is transmitted through the safety interlock device273 for detection by the IR detector 287. It is understood that the IRemitter 285 and IR detector 287 of this embodiment may be positioned atany angle around the radial surface 291 of the seat 271. The IR blockinglayer 275 prevents infrared electromagnetic radiation from outsidesources (e.g., sunlight) from reaching the IR detector 287 when theadministration feeding set 295 is loaded on the pump. It is envisionedthat portions of the radial surface 281 of the electromagnetic radiationpropagation affecting member 279 may have IR blocking material thereon.In that event, the electromagnetic radiation propagation affectingmember 279 is preferably keyed with structure (not shown) on the seat271 so that the IR emitter 285 and IR detector 287 are unblocked. Avisible light detector (not shown) may be present for use in detectingambient light as in earlier embodiments of the invention.

The safety interlock device 273 of this embodiment may be constructed bya “co-injection molding” process also referred to as a “two-shotinjection molding” process. The process includes injection molding thesafety interlock device 273 with the electromagnetic radiationpropagation affecting member 279 comprising an infrared radiationtransmissive material (e.g., light transmissive thermoplastic polymerresin) together with the IR blocking layer 275 (e.g., an opaquethermoplastic polymer resin). Other variations of this embodiment mayinclude the use of a visible light blocking material (e.g.,thermoplastic polymer resin mixed with red dye) instead of an IRblocking material to allow infrared electromagnetic radiation to passthrough the safety interlock device but prevent visible light frompassing through the device.

FIG. 11 is a state diagram illustrating the various conditions thecontroller 77 (FIG. 4) may encounter when operating the softwaresubsystem 82 to determine if the safety interlock device 61 is properlyloaded on the pump. The state diagram has application to otherembodiments, but will be described in respect to the first embodiment.As shown in FIG. 11, for the controller to provide a “SET LOADED”status, the status of the IR emitter 105 and IR detector 109 must be“ON” and the status of the visible light detector 111 must be “OFF”. Anyother combination of status indications from the IR emitter 105, IRdetector 109 and visible light detector 111 results in a “FAULT” statusbeing indicated by the controller. The “FAULT” status will prompt theuser to check the loading of the safety interlock device 61 and willprevent the pump 1 from operating. Once the feeding set 5 is properlyloaded, the controller 77 will sense a “SET LOADED” condition andinitiate operation of the pump 1. During operation of the pump, the IRemitter 105 may operate continuously so that the safety interlock statusis continuously monitored and if the status changes from “SET LOADED” to“FAULT”, the controller 77 will stop operating the pump 1 and enter analarm condition. Optionally, the IR emitter 105 may be operatedintermittently with brief pulses of infrared electromagnetic radiationbeing transmitted at a set time interval to the IR detector 109 so thatthe safety interlock status is continuously monitored. The visible lightdetector 111 may continuously check for the presence of visible light sothat if the safety interlock 61 is removed from the seat 91 and allowsvisible light into the recess, the visible light detector 111immediately senses this condition and signals the controller 77 to enteran alarm condition. The visible light detector 111 may operateintermittently without departing from the scope of this invention.

FIG. 12 shows a seat 301 and safety interlock device 303 of a seventhembodiment of the present invention. In this embodiment, the safetyinterlock device 303 is made of an infrared radiation opaque materialand has an opening 307 passing from the top surface 309 to the bottomsurface 311 of the device. The opening 307 is configured to break thebeam of infrared radiation (indicated at A7) from the IR emitter 313 viadiffraction into a series of spaced apart beams (indicated at A8 a thruA8 e) that are detected by a series of IR detectors 321 a through 321 elocated below the seat 301 in the housing 327. In the illustratedembodiment the IR emitter 313 is located in an alcove 331 above thesafety interlock device 303 and the IR detectors (321 a-321 e) arelocated in an alcove 335 below the safety interlock device 303. The IRdetectors 321 a through 321 e are spaced apart a distance such that theinfrared radiation that is diffracted by the opening 307 impinges on theIR detectors. It is understood that the IR emitter 313 could be belowthe safety interlock device 303 and that the IR detectors 321 a-321 ecould be above the safety interlock device or in some other arrangementwithout departing from the scope of this invention. A visible lightemitter and array of visible light detectors (not shown) could be usedin place of the IR emitter 313 and IR detectors 321 a-321 e.

In the embodiment of FIG. 12, the infrared radiation from the IR emitter313 diffracted by the safety interlock device 303 so that the infraredradiation from the IR emitter is detected by the IR detectors 321 a thru321 e when the interlock device 303 is properly located on the seat 301.The number of detectors 321 a-321 e may be other than shown in thisembodiment without departing from the scope of the present invention.When the interlock device 303 is not present, infrared radiation fromthe IR emitter 313 is seen by the middle IR detector 321 c (broadly, asecond detector), but not by the other detectors 321 a, 321 b, 321 d,321 e. The interlock device 303 is preferably keyed (not shown) to thehousing 327 to assure proper positioning. A visible light detector (notshown) may also be used to detect ambient visible light as in earlierembodiments of the invention.

FIG. 13 shows a seat 381 and a safety interlock device 385 of an eighthembodiment of the present invention. In this embodiment, the safetyinterlock device 385 has an electromagnetic radiation propagationaffecting member 387 made of a material capable of transmitting infraredradiation. The electromagnetic radiation propagation affecting member387 has a layer of material 389 on the top surface of the member that isopaque to the transmission of IR. The opaque layer 389 has an opening391 that breaks the single infrared radiation beam A9 from the IRemitter 393 via diffraction into a series of spaced apart beams A10 athrough A10 e that are detected by respective IR detectors 395 a through395 e when the safety interlock device 385 is properly seated in thepump. When the propagation affecting member 387 is removed from the seat381, only the IR detector 395 c sees the infrared radiation from the IRemitter 393. It will be understood that the number of IR detectors 395a-395 e may be other than shown. It is further understood an IR detectorother than IR detector 395 c can see infrared radiation or more than oneIR detector can see the infrared radiation when the propagationaffecting member 387 is removed from the seat 381. One can also switchthe orientation of the group of IR detectors 395 a-395 e to be in thelower portion of seat 381 and the IR emitter or IR emitters in the upperportion of the seat. A visible light emitter and visible light detectors(not shown) could be used in place of the IR emitter 393 and IRdetectors 395 a-395 e. In that event, the electromagnetic radiationpropagation member would be capable of transmitting visible light, buthave a layer (like layer 389) that is opaque to visible light. Moreover,another visible light detector could be used in this eighth embodimentas in prior embodiments. The interlock device 385 is preferably keyed(not shown) to assure proper positioning.

FIG. 14 shows a seat 421 and a safety interlock device 461 of a ninthembodiment of the present invention. The seat 421 is part of a pump 401that is illustrated in block diagram form in FIG. 16. The pump 401mounts a feeding set 405 including tubing 455 and a safety interlockdevice 461. The feeding set 405 may be substantially the same as thefeeding set 5 shown in FIG. 3. A pumping device 423 includes a rotor 437driven by a motor 425. The rotor 437 can engage the tubing 455 to pumpfluid to a patient, substantially as described in previous embodiments.This embodiment includes an IR emitter 427, an IR detector 429, avisible light emitter 433, and a visible light detector 435 inrespective alcoves in the housing 439 (FIG. 14). In this embodiment, theIR emitter 427 and the IR detector 429 are arranged at an approximately90 degree angle with respect to each other and the visible light emitter433 and the visible light detector 435 are arranged at an approximately90 degree angle with respect to each other. Other relative angles arealso possible. Generally speaking, the IR detector 429 is locatedrelative to the IR emitter 427 so that in the absence of the safetyinterlock device 461, the infrared radiation emitted by the IR emitterwill not impinge upon the IR detector. Both the IR emitter 427 andvisible light emitter 433 are arranged generally perpendicular to theimmediately adjacent side of the safety interlock device 461 whenproperly mounted on the pump 401. Moreover in this and otherembodiments, the gap between the emitters 427, 433 and the safetyinterlock device 461 is preferably small in relation to the diameter ofthe safety interlock device (e.g., nominally 0.005 inches or about 0.13mm). The safety interlock device 461 of this embodiment is transmissiveto infrared radiation but is opaque to visible light. In other words,the interlock device 461 filters out visible light but passes infraredradiation.

The infrared signal emitted by the IR emitter 427 is diffused andreflected in the safety interlock device 461 such that the signalstrikes the IR detector 429 when the feeding set 405 is properly loaded.The seat 421 and safety interlock device 461 of this embodiment areespecially useful in operating in a dark room since the visible lightemitter 433 provides a second electromagnetic radiation signal (e.g., ablue light) that substitutes for visible light not present in a darkroom. The control system of this embodiment first pulses the IR emitter427 until the IR detector 429 receives a signal recognizing that thesafety interlock device 461 is loaded. Next, the visible light emitter433 is activated to send a light signal that is blocked by the safetyinterlock device 461 if the safety interlock device is correctly locatedin the seat 421. The visible light detector 435 is operated to check forthe visible light signal and to detect excess ambient light. If eithercondition is detected (i.e., light from emitter 433 or excess ambientlight), a controller 477 activates an alarm that warns the operator tocheck the alignment of the feeding set 405 and does not allow the pump401 to operate until the condition is corrected. The blockage of ambientlight by the safety interlock device 461 causes the controller 477 torecognize that the set is loaded and the pump may be operated. The pump401 detects a fault condition if the visible light detector 435 detectsthe visible light signal from the visible light emitter 433 after the IRdetector 429 detects the presence of the safety interlock device 461.

Referring to FIG. 16, the controller 477 has a microprocessor 479 thatcontrols pump electronics 480 that operate the motor 425. The controller477 includes at least one software subsystem 482 used in detecting theproper positioning of the feeding set 405 on the pump 401. Operation ofthe software subsystem 482 for use in controlling the pump 401 based onwhether the feeding set 405, and in particular the safety interlockdevice 461, is properly positioned on the pump, is given in a flowchartillustrated in FIG. 17. This particular set of instructions operates sothat the IR emitter 427 is turned on and off or “pulsed”. When the pump401 is powered up at 1396, the software initializes at block 1398 bysetting several items to OFF. For example, the IR emitter 427 andvisible light emitter 433 are set to OFF. Similarly, a program featurecalled Ambient Lock is set to OFF, as are program features InstantOutputand Output. Briefly, Ambient Lock is a feature that is triggered toprevent operation of the pump 401 when it is determined that the IRdetector 429 sees infrared radiation from a source other than the IRemitter 427. The InstantOutput is a temporary or preliminary output ofthe software (i.e., whether the pump 401 is to be allowed to beginpumping). Output is the final output of the software used for determinewhether the pump 401 is permitted to operate for pumping fluid.

At the outset as shown in FIG. 17, the function of the softwaresubsystem 482 will be described assuming that the safety interlockdevice 461 has been properly positioned on the pump 401. After theinitialization 1398, the IR emitter 427 is switched (or “toggled”) ON atblock 1400 so that infrared radiation is emitted. If the safetyinterlock device 461 is positioned so that the infrared radiationstrikes the safety interlock device, the propagation of the infraredradiation from the emitter 427 will be affected so that infraredradiation is diffused and reflected within the safety interlock device.Some of the infrared radiation exits the safety interlock device andstrikes the IR detector 429. The software pauses briefly at block 1401after the IR emitter 427 is toggled on and then reads the IR detector429 at block 1402 to determine if it is “ON” (i.e., that infraredradiation is detected). The software subsystem 482 then proceeds to adecision block 1404 where it queries whether the IR detector 429 is ONand either the IR emitter 427 is OFF or the Ambient Lock is ON. In thecase where the safety interlock device 461 is properly positioned, theIR detector 429 is ON, but the IR emitter 427 is ON and the Ambient Lockis OFF. Therefore, the answer to the query at decision block 1404 is“no”. In other words, the IR detector 429 has seen infrared radiationfrom the emitter 427, which is indicative of proper positioning of thesafety interlock device. The software then sets the Ambient Lock to OFFat block 1404 a (which is no change from its initialized condition) andproceeds to another decision block 1406.

In the next decision block 1406, the software subsystem 482 can operateto bypass evaluation of the visible light detector 435 in a situationwhere either the Ambient Lock is ON (because infrared radiation wasdetected by detector 429 when the IR emitter 427 was OFF), or where theIR emitter 427, IR detector 429 and visible light emitter 433 are allOFF. In the present case, Ambient Lock is OFF and both the IR emitter427 and IR detector 429 are ON, so the software proceeds to read thevisible light detector 435 at block 1408. The properly located safetyinterlock device 461 blocks the visible light detector 435 so thereading is OFF. Thus when queried at the next decision block 1410, theanswer is “no” and the program moves to the next decision block 1412.The visible light emitter 433 has not been turned on yet so the programcauses the visible light emitter to be turned on at block 1414 and movesto the end of the program where there is a delay 1415. The InstantOutputand Output were both initialized to OFF so that the pump 401 is not yetallowed to run. After the delay at 1415, the program returns to step1400. The intermittent operation of the IR emitter 427 and conditionaloperation of the visible light emitter 433 provides significant powersavings in operation of the pump 401. This feature is helpful when thepump 401 is operated on battery power.

Proceeding back to the toggling step 1400, the IR emitter 427 is nowturned OFF and the IR detector 435 reads OFF when it is queried at 1404after the delay. As a result, the Ambient Lock stays OFF so that whenthe next decision block 1406 is reached the answer is again in theaffirmative and the visible light detector 435 is read once again at1408. The safety interlock device 461 still blocks the visible lightdetector 435 so the visible light detector is OFF. Unlike the first loopthrough the program steps, the visible light emitter 433 is now on sothe program moves on to set the InstantOutput to ON at block 1416,indicating that the pump 401 should be allowed to operate for pumpingfluid. However, the program may not immediately allow the pump 401 tooperate. As indicated in the next action block 1418, output filteringmay be used before the final Output is given. For instance, the softwaremay require at block 1418 that there be a number of occurrences of theInstantOutput 1416 being set to ON before the final Output 1418 is setto ON. Various algorithms for establishing confidence in the finaloutput of the program could be employed. On the other hand, outputfiltering could be omitted in which case the Output 1418 would beequivalent to the InstantOutput 1416 in every instance. In either case,once the Output 1418 is set to ON, the pump 401 is allowed to operate.Once operation of the pump 401 is permitted, a routine for checking tomake sure the safety interlock device 461 remains in position can beexecuted. In the illustrated embodiment, this is accomplished bycontinued operation of software subsystem 482. It is also envisionedthat the visible light emitter 433 could be turned off again to conservepower. Various ways of operating the IR emitter 427 and visible lightemitter 433 intermittently can be employed within the scope of thepresent invention.

It will be appreciated that there are several circumstances in which thesoftware subsystem 482 would prevent operation of the pump 401 bydetecting fault conditions indicative of the safety interlock device 461of the feeding set 405 not being properly positioned on the pump.Reference is also made to FIG. 15 showing several conditions that canoccur from the implementation of the software instructions found in thesoftware subsystem 482. The conditions shown are not intended to beexhaustive, but representative of likely conditions to occur in theoperation of the pump 401. Until such time as the IR detector 429detects infrared radiation (IR detector “ON”), the software subsystem482 will not allow the pump 401 to operate. In other words, Output 1418will never be set to ON until after the IR detector 429 has at leastonce detected infrared radiation. If the IR detector 429 has never beenON, when the software reaches decision block 1406, the answer will be“no” and the program will proceed to the end of the loop with InstantOutput 1422 set to OFF. Similarly, the visible emitter 433 will not beturned on at 1414 until a point after infrared radiation from the IRemitter 427 has been detected by the IR detector 429. In that case, thesoftware subsystem 482 proceeds from decision block 1406 to turn thevisible emitter 433 is OFF (block 1420) and the InstantOutput is set toOFF (block 1422).

In the first condition or state of FIG. 15, both the IR emitter 427 andIR detector 429 are OFF. This may occur, for example if the IR emitter427 had been ON, but the IR detector 429 did not detect infraredradiation in a previous loop of the software subsystem 482 shown in FIG.17. This would occur, for example if the feeding set 405 has not beeninstalled. At decision block 1406, the answer to the query would havebeen “no”, so the program would have set InstantOutput 1422 to OFF andpassed to the end of the loop. In a second loop, the IR emitter 427 istoggled OFF so that now both the IR emitter and IR detector 429 are OFFas shown in condition 1. This is an indication that the feeding set 405is not in place on the pump 401 (a “fault” condition). We note that thecondition XX in the table of FIG. 15 is meant to indicate not applicableor inactive for the particular component in the specific conditiondescribed.

The second condition of FIG. 15 is the first of the conditions in whichthe feeding set 405 and safety interlock 461 would be detected.Previously, the software subsystem 482 would have cycled through a loopin which the visible light emitter 433 would have been turned on at1414. This prior program loop is represented by condition 6 in which theIR emitter 427 and IR detector 429 are ON, but the visible light emitter433 has not yet been energized so that Output is not yet allowed atblock 1418 to be set to ON. In the second loop, the IR emitter 427 andIR detector 429 are OFF, but when the program reaches block 1408 thevisible light detector 435 is read. Assuming the feeding set 405 isproperly in position, the visible light detector 435 will not be ON sothat the software subsystem 482 finds the feeding set properlypositioned and sets Output 1418 to ON so that the pump 401 may operate.Condition 8 recognizes that in a later loop of the software subsystem482 the IR emitter 427, IR detector 429 and visible light emitter 433may all be ON, but that a reading of OFF for the visible light detector435 still allows results in Output 1418 being set to ON. Conditions 3and 9 are similarly parallel, but in these conditions the visible lightdetector 435 detects light emitted from the visible light emitter 433,thus preventing the pump 401 from being activated to pump fluid to apatient.

Condition 4 illustrates a situation in which ambient electromagneticradiation in the environment surrounding the pump 401 is detected by theIR detector 429. The IR emitter 427 is OFF, so the software subsystem482 may know that the infrared radiation is not coming from the IRemitter. In that event, the software subsystem 482 receives a “yes”answer to the query at block 1404 and then sets AMBIENT LOCK to ON inblock 1404 b. As a result, the software subsystem 482 bypasses at block1406 any evaluation of the presence of visible light and setsInstantOutput to OFF at 1422. In condition 5, the safety interlockdevice 461 is not in place so that the initial reading at block 1402 ofthe IR detector 429 with the IR emitter 427 ON will be that the IRdetector is OFF. The software subsystem 482 will immediately proceedafter block 1406 through blocks 1420 and 1422 to set Output (at block1418) to OFF without any further evaluation of visible light. The pump401 may also be configured to indicate there is a BRIGHT ambient lightcondition such as might occur if the pump was placed in or near a windowin home use. The indication of bright ambient light would instruct theuser to move the pump to a lower light location.

The software subsystem 482 is also capable of detecting a condition inwhich there is excessively bright ambient light. As shown in condition7, the IR emitter 427 and IR detector 429 are both ON, which isindicative of the feeding set 405 being properly positioned on the pump401. In fact, the set 405 either has not been properly loaded, or animproper set that does not block visible light has been loaded. However,although the visible light emitter 433 is OFF, the visible lightdetector 435 detects visible light. The software subsystem 482 proceedsat decision block 1410, when the visible light detector 435 is ON, toblock 1420 and 1422 so InstantOutput is set to OFF and the pump 401cannot run.

Another software subsystem 484 that could be used to operate thecontroller 477 of the pump 401 is illustrated in FIG. 18. In this systemfor detecting proper placement of the feeding set 405 including thesafety interlock device 461, the IR emitter 427 is not turned off and on(i.e., it is not “pulsed”). Thus after the initialization step 1428, theIR emitter 427 is turned on at block 1430 and remains on while the pump401 is powered. As illustrated in condition 1 in the table of FIG. 19showing selected operating conditions of the software subsystem 484 ofFIG. 18, the only time the IR emitter 427 is OFF is when the pump 401 isnot yet turned on. Referring again to FIG. 18, the software subsystem484 delays at block 1431 after the IR emitter 427 is turned on beforereading the IR detector 429 at block 1432. The software subsystem 484conditions any further checks for confirming the feeding set is properlypositioned on the detection of infrared radiation by the IR detector 429at block 1433. Condition 2 illustrates the situation where the IRemitter 427 is on, but infrared radiation is not detected by the IRdetector 429. Once the IR detector 429 detects infrared radiation, theprogram proceeds in a first loop to read the visible light detector 435at block 1434 to make certain the visible light detector is OFF (block1435), and then turns the visible light emitter 433 ON at block 1436.After a delay at block 1437, the software subsystem 484 proceeds to asecond loop in which the software subsystem 484 confirms that visiblelight is blocked at 1435 and because the visible light emitter 433 isfound to be ON at 1438 sets InstantOutput to ON at block 1440. Assumingno further output filtering, Output is set to ON at block 1442 and thepump 401 is permitted to operate. However if visible light is detected(i.e., at block 1434) prior to activation of the visible light emitter433, the visible light emitter is prevented from being turned on. Inthat case, the software subsystem 484 will proceed to block 1444 to turnthe visible light emitter 433 off, and at block 1446 to setInstantOutput to OFF. Detection of visible light by the visible lightdetector 435 prior to activation of the visible light emitter is shownin condition 3 of FIG. 19.

Conditions 4 and 6 both result in the software subsystem 484 settingOutput 1442 to ON and allowing the pump 401 to operate because thefeeding set and safety interlock device 461 are detected. Conditions 5and 7 illustrate circumstances in which the detection of visible lightby the visible light detector 435 prevents operation of the pump eventhough infrared radiation has been detected by the IR detector 429. Incondition 7, the visible light detector 435 may be detecting eitherlight from the visible light emitter 433 or from ambient. In eithercase, the pump 401 is not permitted to operate. In FIGS. 17 and 18 othervariations may be described by tracing a path through the flow chart, asshown

FIGS. 20 and 21 show a fragmentary portion of a pump 601 adjacent a seat602 of the pump, and safety interlock device 603 of a tenth embodimentof the present invention. The safety interlock device 603 comprises amaterial that transmits both infrared radiation and visible light. Thesafety interlock device 603 includes a blocking portion 607 that isopaque to the transmission of visible light so that the visible light isnot transmitted to the visible light detector 609 when the safetyinterlock device is loaded on the pump. The safety interlock device 603includes a key 613 that is received in a corresponding slot 615 in thepump housing so that the safety interlock device 603 must be alignedwith the blocking portion 607 generally adjacent the visible lightdetector. In the illustrated embodiment, the key 613 is a protrusionextending from the safety interlock device 603 but it is understood thatthe key and the corresponding slot 615 could be other shapes and sizeswithout departing from this invention. Other structures for keying theposition of a safety interlock device in a pump may be used within thescope of the present invention.

When the safety interlock device 603 is loaded in the pump 601 infraredelectromagnetic radiation from the IR emitter 616 is diffused andreflected through the safety interlock device and detected by the IRdetector 617 to verify that the set has been loaded. Next, the visiblelight detector 609 will check for visible light in the pump 601 will notdetect any because of the location of the blocking portion 607 of thesafety interlock device 603 that blocks visible light. In the embodimentof FIG. 20, the visible light emitter 619 will be emitted, sending avisible light signal into the safety interlock device 603. The visiblelight signal will not be transmitted to the visible light detector 609because of the present of the blocking portion 607 and the controlsystem of the pump 601 will allow the pump to operate.

FIG. 22 shows a fragmentary section of a pump 701 including a seat 702,and safety interlock device 703 of an eleventh embodiment of the presentinvention. The safety interlock device 703 is made of a material thattransmits infrared radiation, but blocks electromagnetic radiation inthe visible range so that the visible light is not transmitted to avisible light detector 709 when the safety interlock device is loaded onthe pump 701. Other suitable constructions for passing electromagneticradiation of one wavelength and blocking electromagnetic radiation ofanother wavelength may be employed within the scope of the presentinvention. An arrangement of visible and infrared emitters and detectorslike that shown in FIG. 20 may be employed in the eleventh embodiment,although different arrangements are also possible.

The safety interlock device 703 comprises an outer member 704 and aninner member 706. The outer member includes an upper tubular portion708, a lower tubular portion 710 and an annular flange 712. The annularflange has upper and lower annular channels 714. In the illustratedembodiment, the channels allow less material to be used, but have noeffect on the operation of the safety interlock device 703. A first tubesection 757 of a feeding set is received in the upper portion 708 of theouter member 704 of the safety interlock device 703 and a second tubesection 763 is received over the lower portion 710 of the outer member.

The outer member 704 is made of the material that selectively blocksvisible light and passes infrared radiation. The inner member 706 can bemade of the same material as the outer member, or of a differentmaterial. However, the inner member 706 is substantially opaque toelectromagnetic radiation in the infrared range and also in the visiblerange, and is also preferably highly reflective. In the illustratedembodiment, the inner member 706 is made of the same material as theouter member 704, but is white in color. The inner member 706 can beformed as one piece with the outer member 704, such as by a dualinjection or extrusion process. Additionally, the outer and innermembers 704, 706 could be made as separate pieces and attached to eachother in a suitable manner such as bonding or welding. The inner member706 is positioned in the optical path of the infrared radiation thatenters the safety interlock device 703, and is disposed between theinfrared radiation path and first tube section 757. Accordingly, anouter surface of the inner member 706 defines an “inner boundary region”in this eleventh embodiment for reflecting infrared radiation. The innermember 706 inhibits the loss of internal reflection of infraredradiation that might be caused by the presence of certain liquids (e.g.,water) flowing in the tube 757. Thus, a strong reflection of infraredradiation to the infrared radiation detector (not shown) can be maderegardless of the optical characteristics of the fluid flowing throughthe tube 757.

When introducing elements of the present invention or the preferredembodiment(s) thereof, the articles “a”, “an”, “the” and “said” areintended to mean that there are one or more of the elements. The terms“comprising”, “including” and “having” are intended to be inclusive andmean that there may be additional elements other than the listedelements. Moreover, the use of “up”, “down”, “top” and “bottom” andvariations of these terms is made for convenience, but does not requireany particular orientation of the components.

As various changes could be made in the above without departing from thescope of the invention, it is intended that all matter contained in theabove description and shown in the accompanying drawings shall beinterpreted as illustrative and not in a limiting sense.

1. A method of using a feeding set on an enteral feeding pump, saidfeeding set having an interlock device adapted to be inserted into arecess of the enteral feeding pump, said method comprising: insertingthe interlock device into the recess of the enteral feeding pump;intermittently emitting infrared radiation in a direction for strikingthe inserted interlock device; transmitting and internally reflectingthe infrared radiation within the interlock device to redirect theinfrared radiation toward a first detector when the interlock device isproperly inserted in the pump recess; detecting with the first detectorthe infrared radiation redirected within the interlock device;intermittently energizing a visible light emitter only after infraredradiation has been detected by the first detector; filtering visiblelight with the interlock device to prevent transmission through theinterlock device; reading a second detector to verify that visible lightemitted by the visible light emitter has been blocked; and enablingoperation of the enteral feeding pump to pump nutrient liquid in thefeeding set in response to detection of infrared radiation by the firstdetector and the verification that no visible light is detected by thesecond detector.
 2. A method as set forth in claim 1 wherein the step ofinserting the interlock device into the recess comprises aligning a keyon one of the interlock device and pump with a slot on the other of theinterlock device and pump and moving the interlock device onto the pumpso that the key is received in the slot.
 3. A method as set forth inclaim 1 further comprising attaching a conduit to the interlock device.4. A method as set forth in claim 3 wherein the step of attaching aconduit to the interlock device comprises attaching a first end of theinterlock device to a first conduit section and attaching a second endof the interlock device to a second conduit section.
 5. A method ofusing a feeding set on an enteral feeding pump, said feeding set havingan interlock device adapted to be inserted into a recess of the enteralfeeding pump, said method comprising: inserting the interlock deviceinto the recess of the enteral feeding pump; emitting electromagneticradiation in a direction for striking the inserted interlock device;detecting at least a portion of the electromagnetic radiation strikingthe interlock device when the interlock device is properly inserted inthe pump recess; and enabling operation of the enteral feeding pump topump nutrient liquid in the feeding set in response to the detectedelectromagnetic radiation.
 6. The method as set forth in claim 5,wherein emitting electromagnetic radiation comprises operating first andsecond electromagnetic radiation sources and wherein detecting theelectromagnetic radiation striking the interlock device comprisesdistinguishing between electromagnetic radiation emitted by the firstsource from electromagnetic radiation emitted by the second source. 7.The method as set forth in claim 6, wherein enabling operation of theenteral feeding pump comprises enabling the enteral feeding pump to pumpnutrient liquid in the feeding set in response to the detectedelectromagnetic radiation being emitted by the first source and notemitted by the second source.
 8. The method as set forth in claim 6,wherein the electromagnetic radiation emitted by the first sourcecomprises infrared radiation and the electromagnetic radiation emittedby the second source comprises visible light.
 9. The method as set forthin claim 6 wherein the electromagnetic radiation emitted by the firstsource comprises infrared radiation and the electromagnetic radiationemitted by the second source comprises ambient light.
 10. The method asset forth in claim 5, wherein emitting electromagnetic radiationcomprises operating a first electromagnetic radiation source and whereindetecting the electromagnetic radiation striking the interlock devicecomprises operating a first electromagnetic radiation detector, andfurther comprising disabling operation of the enteral feeding pump inresponse to the first detector detecting electromagnetic radiationemitted by a source other than the first source.
 11. The method as setforth in claim 5, wherein emitting electromagnetic radiation comprisesoperating a first electromagnetic radiation source intermittently togenerate an alternating pattern of emitter activations anddeactivations, said first source emitting electromagnetic radiationduring the emitter activations and not emitting electromagneticradiation during the emitter deactivations.
 12. The method as set forthin claim 11, further comprising detecting electromagnetic radiationstriking the interlock device during at least one of the emitterdeactivations thereby indicating the interlock device is improperlyinserted in the pump recess and disabling operation of the enteralfeeding pump in response thereto.
 13. A method as set forth in claim 5further comprising attaching a conduit to the interlock device.
 14. Amethod as set forth in claim 13 wherein the step of attaching a conduitto the interlock device comprises attaching a first end of the interlockdevice to a first conduit section and attaching a second end of theinterlock device to a second conduit section.
 15. A method forcontrolling a pumping apparatus capable of mounting a pump set having asafety interlock device thereon, the method comprising: emittingelectromagnetic radiation from a first source of electromagneticradiation in a direction for striking said safety interlock device ofthe pump set; activating a first electromagnetic radiation detector todetect electromagnetic radiation striking the first detector; emittingelectromagnetic radiation from a second source of electromagneticradiation in a direction for striking said safety interlock device ofthe pump set; activating a second electromagnetic radiation detector todetect electromagnetic radiation striking the second detector; andcontrolling the pumping apparatus to operate for pumping fluid in thepump set only when electromagnetic radiation emitted from the firstsource is detected by the first detector and when the second detectordoes not detect electromagnetic radiation.
 16. The method as set forthin claim 15 further comprising placing a safety interlock device in aposition on the pumping apparatus wherein electromagnetic radiation fromthe first source strikes the safety interlock device and is directed bythe safety interlock device to the first detector.
 17. The method as setforth in claim 15 wherein emitting electromagnetic radiation from thefirst source comprises emitting infrared radiation and emittingelectromagnetic radiation from the second source comprises emittingvisible light.
 18. The method as set forth in claim 15 wherein emittingelectromagnetic radiation from the first source comprises operating saidfirst source intermittently to generate a pattern of emitter activationswherein electromagnetic radiation is emitted from the first source. 19.The method as set forth in claim 18 wherein activating the firstdetector comprises operating the first detector intermittently in aseries of detector activations to detect the presence of electromagneticradiation from the first source.
 20. The method as set forth in claim 19wherein the number of activations of the radiation detector is greaterthan the number that the number of activations of the radiation emitter.21. The method as set forth in claim 19 wherein said detectoractivations and said emitter activations have a ratio of about 2:1. 22.The method as set forth in claim 15 wherein said step of emittingelectromagnetic radiation from a second source occurs only after thefirst detector has detected electromagnetic radiation from the firstsource